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Volume 72, Number 3, 2020 |
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THEORETICAL, MATHEMATICAL, AND COMPUTATIONAL PHYSICS |
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Dependence of universe deceleration parameter on cosmological constant: mechanism of vacuum pressure excitation by matter
D.YU. TSIPENYUK, W.B. BELAYEV
Rom. Rep. Phys. 72, 113 (2020)
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Article no. 113:
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Abstract. Based on Sakharov's idea of a
'metrical elasticity' of space, i.e., of the emergence of a generalized force, preventing
distortion of space, we detect the pressure of the vacuum as per the geometry of the space around the
local gravity system. The gravitational defect of mass is interpreted as the transfer of energy to the
vacuum, which becomes apparent from its deformation. We determine the gravitational impact of matter
on the vacuum and opposite in the sign pressure of it in case of weakly gravitating static centrally
symmetric distribution of matter using appropriate solution of Einstein's equations. A possibility to
extend the obtained results to arbitrary gravitational systems is evaluated. A non-conservation of
energy in gravitational systems is interpreted by the Extended Space Model (ESM) as the rotation of
the energy-momentum vector in 5-dimensional space. A proposed approach to determining pressure as a
source of gravity leads to a revision of the dependence of the deceleration parameter of the Universe
on the density parameters. Under this condition we examine the ratio between the density parameters of
dark energy and cosmological constant depending on the deceleration parameter.
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Simulations and analysis of the first black hole populations
R.A. BALASOV, L.I. CARAMETE
Rom. Rep. Phys. 72, 114 (2020)
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Article no. 114:
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Abstract. We simulate various black hole
populations using the GIZMO code package for cosmological N-body/Smoothed-particle hydrodynamics
(SPH) problems. The objective of this analysis is to use the results of the simulations in order
to compare them with the present black hole mass distribution. In doing this, we can predict the
initial population of black holes, the mass distribution and the black hole merger rate, which will
be a direct contribution to the future gravitational waves observatories (such as the LISA Space
Mission).
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Determining the output port from the distance
IULIA GHIU
Rom. Rep. Phys. 72, 115 (2020)
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Article no. 115:
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Abstract. In this paper we discuss the
following scenario. Suppose that two distant observers share an entangled state of two D-level
systems. The two observers, Alice and Bob, have to send randomly their particles through a multi-input
multi-output device. The task is to determine the nature of this device or black-box, such that Alice
will be able to determine with certainty the output port of Bob's particle. We prove that this
black-box is the multi-input-port quantum sorter. Further, we investigate if it is possible to
determine the output port in the case when three observers are involved by analyzing the cases
when the Greenberger-Horne-Zeilinger (GHZ) state and the W state are used.
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Vortex solutions in atomic Bose-Einstein condensates via the Adomian decomposition method
TIBERIU HARKO, MAN KWONG MAK, CHUN SING LEUNG
Rom. Rep. Phys. 72, 116 (2020)
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Article no. 116:
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Abstract. We study the dynamics of vortices
with arbitrary topological charges in weakly interacting Bose-Einstein condensates using the Adomian
Decomposition Method to solve the nonlinear Gross-Pitaevskii equation in polar coordinates. The
solutions of the vortex equation are expressed in the form of inginite power series. The power series
representations are compared with the exact numerical solutions of the Gross-Pitaevskii equation for
the uniform and the harmonic potential, respectively. We find that there is a good agreement between
the analytical and the numerical results.
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Chaotic and solitonic solutions for a new time-fractional two-mode Korteweg-de Vries equation
MARWAN ALQURAN, IMAD JARADAT, SHAHER MOMAN, DUMITRU BALEANU
Rom. Rep. Phys. 72, 117 (2020)
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Article no. 117:
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Abstract. The two-mode Korteweg-de Vries
(TMKdV) equation is a nonlinear dispersive wave model that describes the motion of two different
directional wave modes with the same dispersion relations but with various phase velocities,
nonlinearity, and dispersion parameters. In this work, we study the dynamics of the model analytically
in a time-fractional sense to ensure the stability of the extracted waves of the TMKdV equation.
We use the fractional power series technique to conduct our analysis. We show that there is a
homotopy mapping of the solution as the Caputo time-fractional derivative order varies over (0,1]
and that both waves have the same physical shapes but with reflexive relation.
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ATOMIC, MOLECULAR, AND NUCLEAR PHYSICS |
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Competition between 296Lv α decay and fission as function of the excitation energy
M. MIREA, A. SANDULESCU
Rom. Rep. Phys. 72, 202 (2020)
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Article no. 202:
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Abstract. The deformation energy for the 296Lv superheavy element
is calculated in the framework of the macroscopic-microscopic model based on the the Woods-Saxon two-center shell model. The
inertia is obtained within the cranking approach. The superasymmetric fission and the near symmetric fission of 296Lv nucleus
are investigated. The fission paths are obtained by minimizing the action integral constrained by a final configuration pertaining to
the fission or to the α-decay process. In both cases, the potential barrier exhibits a two-humped structure characterized by a
deep second well. The ratio between α-decay and cold fission decay probabilities are reported for different excitation
energies of the parent nucleus.
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OPTICS AND PHOTONICS, PLASMAS, LASER AND BEAM PHYSICS |
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Mid-infrared nanophotonics for biochemical sensing: a review
O. TAKAYAMA
Rom. Rep. Phys. 72, 408 (2020)
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Article no. 408:
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Abstract. The mid-infrared (IR) wavelength region is widely utilized for
absorption spectroscopy to detect molecules in gas, liquid, and solid phases by taking the advantage of characteristic infrared
absorption peaks unique to molecular bonding. MidIR absorption spectroscopy offers a unique label-free detection method with a
wide variety of applications from environmental monitoring to medical diagnosis. However, the challenge lies in the huge mismatch
of molecular sizes, typically on the order of nanometer as opposed to microns of mid-IR wavelengths, making detection of low
concentration of them extremely challenging. Various nanophotonic phenomena enable us to localize mid-IR light at nanoscale
to enhance light absorption by molecules and thus sensitivity. We present an overview of nanophotonic phenomena, such as
waveguide modes, both propagating and localized plasmon modes, together with micro- and nanostructured platforms that host
these phenomena, including dielectric planar waveguides, photonic crystals, plasmonic, and phononic nanostructures.
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Cleansing data from the high-power laser system in ELI-NP: a holistic system approach
G. KOLLIOPOULOS, G. PRODAN, B. BOISDEFFRE, I. DANCUS
Rom. Rep. Phys. 72, 409 (2020)
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Article no. 409:
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Abstract. A method aiming to reduce the amount of data that should be
stored at the ELI-NP data center is presented here. Based on a holistic system approach ([1] L. Bertalanffy, General System Theory,
George Braziller, Inc. 1968) on the High Power Laser System (HPLS), it consists of a binary classifier which marks the records
either as 'useful' or 'useless'.
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Ultrashort pulses in photonic crystals made of carbon nanotubes with nonlinear absorption
I.S. DVUZHILOV, Y.V. DVUZHILOVA, N.N. KONOBEEVA, M.B. BELONENKO
Rom. Rep. Phys. 72, 410 (2020)
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Article no. 410:
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Abstract. In this paper, we consider the problem of the propagation of
three-dimensional ultrashort optical pulses in a photonic crystal made of zig-zag carbon nanotubes under the condition of
nonlinear absorption and amplification. The nonlinear absorption is described phenomenologically using data from real experiments.
The possibility of stable optical pulse propagation under the conditions of external pump and damping field is shown. We analyze
the dependence of the pulse shape on various parameters of the medium, such as the period of carbon nanotubes inhomogeneity in a
photonic crystal and the modulation depth of the refractive index.
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Travelling-wave analysis of extended cavity diode lasers
V. TRONCIU, B. ARAR, H. WENZEL
Rom. Rep. Phys. 72, 411 (2020)
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Article no. 411:
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Abstract. We report results of numerical simulations of the dynamic
properties of single-transverse mode diode lasers subject to an external optical feedback provided by a volume holographic
Bragg grating. We use the traveling-wave model for the simulation and analysis of the nonlinear dynamics of the considered devices.
We show that the numerical results obtained for a sample device are in a good agreement with the experiment. We investigate the
influence of relevant device parameters, such as front and rear facet reflectivities and intra-cavity transmission losses on the
laser behaviour.
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Nonlinear waves in a crystal characterized by the jump switching between self-focusing and defocusing Kerr nonlinearities
S.E. SAVOTCHENKO
Rom. Rep. Phys. 72, 412 (2020)
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Article no. 412:
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Abstract. In this paper, we propose a new optical nonlinearity model
describing a sharp change from a self-focusing Kerr-type nonlinearity to a defocusing one and vice versa, depending on the
electric field amplitude. Three new types of transverse electric nonlinear surface waves can propagate along the interfaces
between media characterized by nonlinearities of the proposed type. The light beam propagating along the interface
significantly changes the optical properties of regions near that interface. The structure of nonlinear surface waves
and peculiarities of the optical domain formation near the interface are described analytically.
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CONDENSED AND SOFT MATTER PHYSICS |
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Influence of a transverse magnetic field and of hydrostatic pressure on the elasticity state of anisotropic magnetorheological elastomers
I. BICA, E. M. ANITAS, M. BUNOIU
Rom. Rep. Phys. 72, 505 (2020)
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Article no. 505:
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Abstract. We manufacture an anisotropic magnetorheological elastomer
(aMRE) based on silicone rubber and carbonyl iron microparticles. A plane capacitor having aMRE as dielectric material is
obtained by placing the aMRE between two electroconductive disks, followed by polymerization in a transverse magnetic field.
The electrical capacitance of the capacitor in the magnetic field, and respectively under mechanical compression is
measured by using a new experimental setup. It is shown that in a magnetic field, the capacitance depends sensibly on the
direction of application of the magnetic field intensity. Under the action of mechanical compression, the capacitance is
equivalent to the one measured when the transverse magnetic field is applied. The modification of the electric capacitance is
the effect of magneto-striction of aMRE in the magnetic field. We describe the observed effects by using the dipolar
approximation and linear elasticity theory for small deformations.
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Microstructural and electrical transport properties of RBa2Cu3O7-γ (R=Y, Pr) based thin films and ramp-type Josephson junctions
V. LECA, N.D. SCARISOREANU, M. DINESCU
Rom. Rep. Phys. 72, 506 (2020)
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Article no. 506:
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Abstract. The results of a study on the fabrication and properties of
RBa2Cu3O7-γ (R = Y, Pr) - based thin films and ramp-type Josephson junctions are presented. The films were grown on (001)
SrTiO3 substrates by radio frequency plasma-assisted pulsed laser deposition (PLD) or by conventional PLD and their
morphological, structural, and electrical properties were analyzed. The ramp morphology and the quality of the interfaces
with the barrier and the top-electrode were found to be critical factors limiting the transport of charge carrier between
the superconducting electrodes of the junctions.
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Ferromagnetism of manganese-aluminium alloyed with 0-3% carbon from direct induction melting and subsequent annealing
T. CHAROENSUK, P. SAETANG, C. RUTTANAPUN, C. PHROMPET, S. PINITSOONTORN, C. SIRISATHITKUL
Rom. Rep. Phys. 72, 507 (2020)
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Article no. 507:
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Abstract.The transformation from ε to τ phase is investigated in
manganesealuminium (Mn55Al45) alloyed by the induction melting. By annealing Mn55Al45 at 450–550 °C
for 2 h, the ferromagnetic τ-MnAl is enhanced at the expense of ε phase. The largest coercivity of 1139 Oe and remanent magnetization
of 3.71 emu/g are obtained after annealing at 550 °C. The additions of 1 and 2% carbon affect the phase and magnetic properties
of Mn55Al45 but the 2 h annealing at 550 °C still leads to the largest coercivity. Interestingly, substantial coercivity
and magnetizations are directly obtained in (Mn55Al45)98C2 and (Mn55Al45)97C3 by the induction melting without
further heat treatments.
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BIOPHYSICS AND MEDICAL PHYSICS |
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Biophysics of protein folding. A short review
CLAUDIA G. CHILOM, AUREL I. POPESCU
Rom. Rep. Phys. 72, 604 (2020)
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Article no. 604:
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Abstract. A cell expresses over 10,000 proteins for metabolism
driving, cellular morphology maintaining, and signaling towards other cells. All these proteins are properly operating only
if they possess a native 3D structure. Protein folding is the dynamical process by which a protein attains its unique
functional native 3D conformation. Two factors mainly contribute to protein folding: the physical and chemical properties
of its amino acids and the influence of the crowded cellular microenvironment of the nascent protein. Although the number
of the intermediate states, starting from linear unfolded nascent chain to the native state, is huge, the folding is very
rapid implying thus energetically favoured folding paths. Protein folding not only generates biologically active structures,
but also protects the protein from degradation by proteases and reduces the probability of abnormal aggregation as in the
case of some diseases (e.g., Alzheimer).
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A nonlinear heuristic model for estimation of Covid-19 impact to world population
SERGEY V. ERSHKOV, VICTOR CHRISTIANTO, ALLA RACHINSKAYA, E. YU. PROSVIRYAKOV
Rom. Rep. Phys. 72, 605 (2020)
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Article no. 605:
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Abstract. In the current model of first approximation, we suggest a
nonlinear heuristic approach by appropriate mathematical modelling, with the main aim estimate the part of humankind which
will survive definitely (in optimistic scenario). As a historical example, let us recall the fate of Inca civilization as
pessimistic scenario. It seems to be natural, by the existing traditions in theoretical biology, to use theory of recurrent
sets (chains of recurrent sets) for describing how population evolves over time. Such an approach actually determines a
non-linear dependence of self-similar rate of evolution process (or dynamics of infected population) in regard to the proper
residual capacity of non-infected part of all the humankind to overcome the pandemic of K-virus (Covid-19). The last is assumed
to be associated with 'potential of the niche for absorbing the infection', defining a catastrophic acceleration (or optimistic
deceleration) for the dynamics of the infected part of population.
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Bioactive phyto-nanosilver particles 'green' synthesized from Clary Sage, Burdock, Southernwood and Asparagus
M.E. BARBINTA-PATRASCU, N. BADEA, C. UNGUREANU, D. BESLIU, S. ANTOHE
Rom. Rep. Phys. 72, 606 (2020)
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Article no. 606:
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Abstract. This study reports the 'green' synthesis and biophysical
characterization of silver nanoparticles (AgNPs) generated from natural extracts of Salvia sclarea (Clary sage),
Arctium lappa (Burdock), Artemisia abrotanum (Southernwood) and Asparagus officinalis (Asparagus), for biomedical purposes.
UV-Vis absorption spectroscopy revealed SPR bands for AgNPs, between 438 and 467 nm. DLS measurements showed the
nano-dimensions of particles ranging from 51.05±0.99 to 123.6±2.05 nm. Zeta potential values of these biogenic AgNPs
revealed their good physical stability. The developed AgNPs exhibited impressive antioxidant potential (evaluated by
chemiluminescence and ABTS methods) and also antibacterial effect against Escherichia coli bacterium. These materials
could be exploited in biomedical field to fight against bacteria and to combat oxidative stress by scavenging short-life
& long-life free radicals.
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Removal of repetitive magnetic interferences upon unshielded fetal magnetocardiograms
B. ARVINTI, A. ISAR, R. STOLZ, M. COSTACHE
Rom. Rep. Phys. 72, 607 (2020)
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Article no. 607:
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Abstract. Fetal magnetocardiograms are highly sensitive to
interferences in unshielded environments, the measurements being realized indirectly. We aimed at removing repetitive
deterministic interferences, applying the Wiener filter in the wavelet domain. An effective compression of data is performed
using the Walsh-Hadamard Transform. Real fetal data has been analyzed, with promising results for the development of an
automated diagnosis system.
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ENVIRONMENTAL AND EARTH PHYSICS |
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Effects of polyethylene glycol and sodium chloride stress on water absorption of magneto-primed triticale seeds
J. ALVAREZ, E. MARTINEZ, V. CARBONELL, M. FLOREZ
Rom. Rep. Phys. 72, 708 (2020)
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Article no. 708:
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Abstract. The effect of drought and salt stress was studied by
generating the same water potential (Ψ) with polyethylene glycol (PEG) and sodium chloride (NaCl). In addition, as
the magneto-priming was demonstrated to be a non-invasive method to improve germination, the study was performed by
comparing water absorption of magnetically treated and non-treated seeds of triticale (X Triticosecale Wittmack)
under stress conditions.
Seeds water uptake was inversely proportional to the PEG and NaCl concentration, although the absorption was greater
for magnetically treated seeds in comparison to the untreated ones (increments up to 11%). Seeds magnetically treated
absorbed more water under the influence of NaCl than PEG, especially with low Ψ levels. The adverse effect of salinity
and drought on water absorption can be circumvented by exposing seeds to magnetic treatment with a stationary magnetic
field induction of 3.71 mT (milliTeslas) during 10 h.
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Experimental characterization of an in-situ spectrotracer used in geophysical explorations
I. RADULESCU, R. STOCHICI, M. R. CALIN, M. VISAN, C. DIACOPOLOS, G. GRIGORAS
Rom. Rep. Phys. 72, 709 (2020)
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Article no. 709:
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Abstract. The selection of an appropriate detector for field
measurements, in case of natural radioactivity, is an important task taking into account constraints given by data
reliability, time and cost effectiveness. This paper provides the necessary data when choosing a portable spectrometer
Gamma Surveyor based on BGO crystal (6.3 in3). The proven efficiency of the crystal, the weaker energy resolution
but still good comparable results with HPGe results, obtained for 238U, 232Th, 40K often makes it a good choice. Thus,
in this paper some functional parameters, as energy calibration, energy resolution and background of the system are analyzed.
In addition, field data, concentrations of radionuclides 238U, 232Th, 40K (ppm) in surface soil on the Bucharest area are
compared with laboratory measurements using HPGe detector. The obtained data, for all three radionuclides, are well
correlated.
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APPLIED AND INTERDISCIPLINARY PHYSICS |
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A Monte Carlo study on the dose distribution in the volume of the glass samples used in dosimetry applications
M. ZADEHRAFI, C. OLARU, G. ORMENISAN, S. CIOBANU
Rom. Rep. Phys. 72, 804 (2020)
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Article no. 804:
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Abstract. In this paper, a Monte Carlo study on the dose distribution
in the volume of the glass samples used in dosimetry applications was performed. Due to the fact that in glass-based dosimetry
the calibration process plays a very important role, it must be carefully approached. In this mater, a study on the
influence of the energy of the involved ionizing radiation as well as the position (rotational plan) of the glass samples
to the resulting dose distribution was done. Three arbitrary photon energy values, namely 100 keV, 150 keV, and 200 keV, and
two angular positions (0 and 45 degrees angle) were chosen. It was shown that when 'reading' the optical parameters of the
exposed glass samples, due to the sensitivity of the dose distribution to energy and position, it is very important to be
done on the best possible aligned samples. It is also recommended to make multiple determinations on the same sample and use
the mean value. By using a mean value, more precise and more accurate values can be obtained, as well as a better evaluation
of the associated budget of uncertainties.
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Physical degradation detection on artwork surface polychromies using deep learning models
L.M. ANGHELUTA, A. CHIROSCA
Rom. Rep. Phys. 72, 805 (2020)
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Article no. 805:
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Abstract. This paper presents the application of a Deep Learning algorithm for
a classified accurate detection of different types of physical damages in artwork polychrome surfaces. The algorithm was trained for
the automated detection of three classes of typical surface deteriorations: cracks, blisters and detachments (losses). The image
sets used in this study were previously recorded for the purpose of detailed surface 3D reconstruction by the means of macro-photogrammetry
of a wood painting. These high-resolution images were captured using 2:1 optical macro magnification with a generous overlapping,
following the 3D reconstruction methodology, and provided high quality details of the surface features to be classified. Specific activation
maps are used to visually emphasize the detected potential deteriorated areas. The purpose of this work was on one hand to validate a process
of reusing photogrammetry image data sets, used 3D reconstruction, for machine learning feature detection training and on the other hand
to provide a starting point for the development of an affordable real-time surface damage assessment system.
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Fourier transform infrared spectroscopic characterization of thermal treated kaolin
R. DEJU, C. MAZILU, I. STANCULESCU, C. TUCA
Rom. Rep. Phys. 72, 806 (2020)
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Article no. 806:
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Abstract. The present paper assesses the chemical
and microstructural characteristics of the kaolin used as admixture in the mortars for the radioactive
waste immobilization. For this purpose, there were used X-ray fluorescence spectroscopy (XRF) methodology
as well as the scanning electron microscopy (SEM) coupled with EDS probe. The optimal values of the
calcination parameters such as temperature and heating plateau that ensure the complete transformation
of the kaolin into metakaolin have been identified by infrared spectroscopy (FTIR). The goal is to
increase the mortar performance by reducing the leaching of the immobilized radionuclides in the
cementitious matrix obtained by recycling of the radioactive concrete resulted from decommissioning
of a VVR-S type nuclear research reactor.
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PHYSICS EDUCATION |
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Dynamic study of torsion using Tracker software
FABIOLA SANDA CHIRIACESCU, B. CHIRIACESCU, CRISTINA MIRON, C. BERLIC, V. BARNA
Rom. Rep. Phys. 72, 904 (2020)
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Article no. 904:
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Abstract. The paper presents an experimental
approach that familiarizes students with the video analysis technique. Herein we investigate the
dynamic study of the torsion for a metal wire by means of video analysis method with Tracker software
and a high-speed camera for data acquisition. The obtained results are in very good agreement with the
theoretical calculations for the employed experimental setup.
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This is an electronic version of Volume 72 Number 3 2020
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